1. Field of the Invention
The invention relates generally to an electronic reprographic system, and more specifically to the method and apparatus for electronically scanning a bound document or other signature-type input documents.
2. Description of the Prior Art
As is well known, a signature-type document is a sheet typically containing four numbered pages which when folded and nested inside one another become one unit of a pamphlet or book. Generally, in order to obtain an electronic image of a plurality of bound or signature-type pages, it is necessary to scan each of the pages independently. Furthermore, scanning the facing page requires the manual repositioning of the book or document to a fixed registration position prior to initiating the scanning operation.
In general, formation of a single copy sheet from two sheets or pages placed on the platen is known in the reprographic art. For example, U.S. Pat. No. 4,731,637 to Acquaviva et al. discloses a registration gate which is retractably insertable having first and second registration sides spaced apart by a preset defined distance. Documents are fed to an imaging station for "two-up" copying with a registered spacing between them determined by a gate thickness. U.S. Pat. No. 4,334,765 to Clark also teaches an apparatus comprising an automatic document feeder in which copies may be reduced in size and placed contiguous one another on both sides of a copy sheet in a sequence facilitating booklet assembly. Also, U.S. Pat. No. 4,783,682 to Maehara discloses a method which comprises correctly aligning a tip position of a copy paper by operating a timer and a counter. When "one-set/two-copy" mode is entered for continuously copying, both a left half and a right half of a two sided original are copied onto individual copying papers. Moreover, an apparatus capable of copying a bound document while eliminating the offset inherent in the copy of the second page is taught in U.S. Pat. No. 4,739,372 to Watanabe. The image forming apparatus disclosed provides dual-page copies of a document that are free of offset. Also included is a fixed scale that provides a scanning start position for the first page of a document, and a movable scale that provides a scanning end position for a second page of a document. U.S. Pat. No. 4,674,864 to Stackenborg et al. also teaches a device having control means for accepting data concerning the width of oppositely located image-free edge zones, whereby said control means ultimately determines the imaging ratio and a final width of the image-free edge zones. An operator need not reinput these data for each copying job.
Another example of a reprographic apparatus intended to facilitate copying a book is found in U.S. Pat. No. 4,659,207 to Maekawa, which discloses a method comprising a switchable mode enabling the starting of an exposure from either one end or the center of a glass platen according to an operation signal. Copies are formed on both sides of a copy paper or on two different copy papers selectively. Moreover, U.S. Pat. No. 4,353,638 to Knechtel discloses an apparatus which produces copies during a forward scanning time and a backward scanning time. During backward scanning, a reflector is interposed in the optical path to further reflect and invert the image exposed on the photoconductive drum. Also, U.S. Pat. No. 4,688,930 to Ohno discloses an original reading apparatus which separately scans a first area and a second area of an original. In a first scanning mode, an optical scanning device first scans a first area of an original and automatically scans sequentially a second area of an original, and vice versa. Moreover, U.S. Pat. No. 4,611,908 to Bush also teaches an apparatus having a means for inputting information on a desired margin size, and in response to this input, an adjustment is made to the location of the reproduced image with respect to the copy sheet.
While the reprographic art presented teaches methods and apparatus for copying books, all appear to be limited to producing output on a standard size copy sheet. Furthermore, because the sheet is of standard size, the copies will generally contain edges that are darkened due to the exposure of the binding region of the book. Generally, the only recourse, for eliminating the effects of the binding region, is to alter the registration of the book and/or magnify the image to fill a greater portion of the copy sheet.
Fortunately, electronic reprographic systems enable the selective scanning of only a predetermined region of an original document. It would be desirable therefore to implement a new and improved system for bound or signature document image scanning utilizing the selective scanning or cropping capabilities of an electronic reprographic system. It is another object of the present invention to provide a simplified method for the operator to select such a scanning mode. It is a further object of the present invention to simplify the operation of registering the bound document on the imaging platen. It is yet another object of the present invention to increase the speed of scanning signature-type documents by scanning the two facing pages of a signature sheet in one scanning pass. It is yet another object of the present invention to decrease the interdocument scanning delay of such a scanning system by scanning both facing pages of a signature sheet in a first direction, indexing a second signature sheet onto the imaging platen and scanning both faces of the second signature sheet in a direction opposite the first direction. It is a final object of the present invention to further decrease the system interdocument delay time while improving document registration by sequentially feeding and registering unbound signature sheets to the imaging platen.
Further advantages of the present invention will become apparent as the following description proceeds and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.